Conventional fireplace assemblies are configured to burn a selected fuel, such as wood, pellets, gas, etc., and this burning of the fuel results in exhaust that contains combustion bi-products. As an example, a wood burning fireplace assembly, such as a stove or insert, is used to burn wood in the firebox, which creates combustion bi-products (solid and gaseous) that exit the firebox as exhaust. Technology has been developed to reduce or otherwise control the emissions from the fireplace assemblies, including catalytic fireplace assemblies and non-catalytic fireplace assemblies that provide for secondary combustion of the exhaust to reduce the emissions.
Conventional catalytic fireplace assemblies having catalytic converters are generally effective in achieving low particulate emissions at low temperatures, but become less effective as temperatures rise. On the other hand, conventional non-catalytic fireplace assemblies having secondary combustion tubes are generally effective in causing secondary combustion of the combustion bi-products to achieve low particulate emissions at high temperatures, but become less effective as temperatures fall. In both cases, a bypass damper may need to be frequently controlled and/or other manual adjustments may need to be made in order to regulate the rate of combustion within the fireplace assembly.